JPH11231061A - Manufacture of scintillator for computer-operated tomographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture of a scintillator by using an inner-diameter saw provided with a saw cutter having an inner-periphery cutting edge coated with diamond. SOLUTION: A plurality of scintillator wafers are stacked and cut with an inner-diameter saw to obtain a plurality of first rod materials. After the rod materials are arranged on a mount to make first gaps 28, the gaps are filled with filling-type reflecting material 114. The inner-diameter saw is used to cut the first rod materials at 90 degrees to the longitudinal direction to obtain second rod materials 118. The second rod materials 118 are arranged on the mount in spaced relationship to provide second gaps 32 similar to the first gaps. Similarly with the first gap 28, the second gaps 32 are filled with the filling-type reflecting material to form a scintillator array. In the method, the frequency of handling operation is minimized and a time is thus saved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to computer tomography (CT) technology, and more particularly, to a detector used in connection with a CT apparatus.

[0002]

BACKGROUND OF THE INVENTION In at least some computer tomography (CT) arrangements, a fan beam projected from an X-ray source is positioned in an XY plane of a rectangular coordinate system (commonly referred to as an "imaging plane"). Are parallelized. This X-ray beam passes through the object to be imaged (eg, a patient). After being attenuated by the object, the X-ray beam is incident on a radiation detector array. The intensity of the X-ray beam received by the detector array depends on the degree of attenuation of the X-ray by the object. Each detector element in the array produces an independent electrical signal, which is a measure of the x-ray beam attenuation at that detector location. The transmission distribution is determined by independently collecting attenuation measurements from all detector elements.

[0003] In known third generation CT systems, the x-ray source and detector array rotate with the gantry in the imaging plane and around the object to be imaged. As a result, the angle at which the X-ray beam traverses the object is constantly changing. Usually, X
The source includes an X-ray tube, which emits an X-ray beam from a focal point. The X-ray detector typically includes a collimator for collimating the received X-ray beam, a scintillator adjacent to the collimator, and a photodiode adjacent to the scintillator.

A multi-slice CT apparatus is used to obtain data on a larger number of cross sections in one scan. Known multi-slice CT devices typically include a detector commonly known as a three-dimensional (3D) detector. In such a three-dimensional detector, a number of detector cells form independent channels arranged in a plurality of rows and columns.

A scintillator for a three-dimensional detector is about 1 ×
It may include a scintillator element with dimensions of 2 × 3 mm. In that case, the gap between the elements has a small value of only a few mils (eg, about 0.004 inches). Various problems arise as a result of such elements having small dimensions and being close to each other. For example, a signal incident on one scintillator element is reflected upward,
Alternatively, the light may be incident on an adjacent element, so that the resolution may be disadvantageously reduced.

[0006] Typically, the scintillator is cut by a precision dicing saw, etching or laser cutting method.
Such cutting is required to obtain the desired dimensions. The most common method for cutting a scintillator uses a diamond saw (diamond saw) outer diameter (OD) saw blade. To cut materials such as ceramics, the outer diameter saw has a diamond coating on the outer periphery of the saw blade. In order to perform accurate cutting while maintaining the rigidity of the saw blade, for example, 10,000 to 30,000 rpm
A very fast rotation speed of m is used. However, if the gap aspect ratio exceeds 10, it may be difficult to achieve a cutting gap of, for example, 4 mils in a ceramic scintillator. In particular, for scintillators having aspect ratios greater than 10, outer diameter saws often result in inaccurate cuts. Moreover, cutting only one scintillator at a time requires multiple handling operations for each three-dimensional array. Such a method is time and money consuming.

For this reason, it is desirable to provide a method for increasing the cutting accuracy of a scintillator for a three-dimensional scintillator. It would also be desirable to provide a method that minimizes the number of handling operations required to manufacture such a scintillator.

[0008]

SUMMARY OF THE INVENTION These and other objects can be achieved by a method for manufacturing a scintillator that includes the step of accurately cutting a large number of ceramic scintillators at once. Using the method of the present invention, ceramic scintillators can be cut at a much faster rate, even when the scintillator has a thickness of several inches and an aspect ratio of more than 10. In more detail according to one embodiment, the scintillator element is cut using an inner diameter (ID) saw. The inner diameter saw has a saw blade having an inner peripheral cutting edge coated with diamond. Because the outer surface of such a saw blade can be tensioned to high stress conditions, the inner saw blade has much greater rigidity than the outer saw blade. Such tensioning allows for accurate cutting even when making very deep cuts.

According to one embodiment, a first bar deposit is obtained by cutting a deposit on a scintillator wafer in a first direction using a diamond-coated inner saw. After separating the first bar deposit into the first bar, the first bar which has been cast in the direction of 90 ° with respect to the first cutting direction using the inner cutting edge having the inner diameter is removed. By cutting, a second bar deposit is obtained. After separating the second bar deposit into a second bar, the second bar is placed on the fixture with a gap between the second bars, and the gap is cast reflector And then grinding the second bar to have the final dimensions to obtain a finished scintillator array.

The above method facilitates producing scintillators with higher accuracy. Furthermore, cutting and casting a small number of large scintillator members reduces handling of small pixels or small arrays to a minimum, thus saving time.

[0011]

FIG. 1 shows a scintillator 2 including a plurality of scintillator elements 24 arranged in an array having a first gap 28 and a second gap 32. FIG.
FIG. The scintillator element 24 is processed from a polycrystalline ceramic scintillator material or a single crystal scintillator material. When the X-ray beam strikes, scintillator element 24 produces a light output signal. The light output is optically coupled to a photodiode array. Each photodiode in such an array produces an independent attenuation signal, and the transmission distribution is determined by collecting the signals from all the photodiodes independently.

To manufacture the scintillator 20, referring to FIGS. 2 and 3, the scintillator wafers 100 are joined together using a low melting point adhesive, a dissolvable adhesive or another temporary adhesive (not shown). Are temporarily combined to form a deposit 104. Inner diameter (ID)
By cutting the deposit 104 using this inner peripheral cutting edge, a first bar deposit 108 is obtained. Inner diameter saws are known in the art. However, to date, such bore saws have not been used in the manufacture of scintillators. The inner saw blade can cut the deposit 104 more accurately than the outer saw blade. Because the inner diameter saw blade is tensioned on the outer diameter side in a high stress state,
Therefore, it has much higher rigidity. After cutting,
By breaking the bond with the temporary adhesive, the first bar deposit 108 is separated into the first bar 110.

Referring now to FIGS. 4 and 5, first bars 110 are arranged in an array 112 and are disposed on a fixture (not shown). At that time, the first gap 28 is provided by separating the first rods 110 from each other. Typically, the width of gap 28 is in the range of 0.5 to 6 mils. According to one embodiment, the width of the gap 28 is about 4 mils and its height / width ratio is up to 30. The gap 28 is then filled with a casting reflector 114, for example made of titanium dioxide (TiO ₂ ) and a castable polymer. After curing, a plurality of arrays 112 are deposited and a second bar deposit 116 is obtained by cutting in a direction perpendicular to the first cutting direction using this inner diameter cutting edge. Then the second
Is separated into a second bar 118.
Such second bars 118 are arranged in an array and placed on a fixture (not shown). In this case, the second gap 32 is provided by separating the second rods 118 from each other. According to one embodiment, the width of the gap 32 is equal to the width of the gap 28.

Referring now to FIG.
Cast reflector 1 similar to the material used to fill the
At 14, the gap 32 is filled. After curing, the array is separated from the fixture and a reflector 114 is provided around the array.
Is cast. After a final grinding finish, a finished scintillator 20 including scintillator elements 24 having dimensions of about 1 × 2 × 3 mm is obtained. Note that the dimensions of the scintillator element may be different from those described above depending on the embodiment.

According to another embodiment, the scintillator 2
A scintillator (not shown) similar to 0 is manufactured,
In this case, the first bar deposit is not separated into the first bars 110. That is, the first bar deposits are arranged in an array and placed on a fixture. In so doing, a first gap is provided by separating the first bar deposits from each other. Such a first gap is similar to gap 28, and material 11
Filled with a cast reflector similar to 4. After hardening, the first cutting direction is perpendicular to the first cutting direction using the inner peripheral cutting edge of the inner diameter.
The second bar deposit is obtained by cutting the bar deposit. The second bar deposits are then arranged in an array and placed on a fixture (not shown). At this time, a second gap similar to the second gap 32 is provided by separating the second bar deposits from each other.

Next, the second gap is filled with a cast reflector similar to the material used to fill the first gap. After curing the reflector, the array is separated from the fixture and a reflector similar to reflector 114 is cast around the array. Next, a plurality of scintillators are cut out from the scintillator array by cutting the scintillator array in the thickness direction of each wafer using the cutting blade having the inner diameter. After the final grinding finish, about 1 × 2 ×
A completed scintillator 20 including a scintillator element having a dimension of 3 mm is obtained. Note that the dimensions of the scintillator element may be different from those described above depending on the embodiment.

The above method facilitates the production of a three-dimensional scintillator. Furthermore, the above method increases the positional accuracy when cutting the three-dimensional scintillator, thereby saving time and reducing waste material. From the above description of some embodiments of the invention, it is apparent that the objects of the invention have been achieved. Although the invention has been described in detail above, the description is merely for the purpose of illustrating the invention and should not be construed as limiting the scope of the invention. Therefore, it is to be understood that the scope of the present invention is limited solely by the appended claims.

[Brief description of the drawings]

FIG. 1 is a perspective view of a scintillator including a plurality of scintillator elements.

FIG. 2 is a perspective view of a deposit on a scintillator wafer.

FIG. 3 is a perspective view of a first bar deposit that has been cut from the deposit shown in FIG. 2;

FIG. 4 is a perspective view of an array of first bars separated from the first bar deposit shown in FIG. 3;

FIG. 5 is a perspective view of a deposit of the array shown in FIG.

FIG. 6 is a perspective view of the array before a final casting step.

[Explanation of symbols]

 Reference Signs List 20 scintillator 24 scintillator element 28 first gap 32 second gap 100 scintillator wafer 104 deposit 108 first bar deposit 110 first bar 112 array 114 casting reflector 116 second bar deposit Object 118 2nd bar

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Matthew R. Scheduler, No. 5328, North Kent Avenue, Whitefish Bay, Wisconsin, United States

Claims (19)

[Claims] 1. A method of manufacturing a scintillator for a computed tomography apparatus using an inner diameter saw having a saw blade having an inner peripheral cutting edge, comprising: combining a plurality of scintillators to form a deposit.
And cutting the deposit with the cutting edge of the inner diameter to obtain a plurality of first bar deposits. 2. The method according to claim 1, wherein the scintillators are temporarily bonded to each other using a low melting point adhesive. 3. The method of claim 1, wherein said scintillator is a polycrystalline ceramic scintillator. 4. The method of claim 1, wherein said scintillator is a single crystal scintillator. 5. The method according to claim 1, further comprising the steps of: separating the first bar deposit into first bars; arranging the first bar on a fixture while being separated by a gap; 2. The method of claim 1, further comprising the steps of: joining the bars together to obtain a first bar array; and casting a reflector on the surface of the first bars and into the gap. Method. 6. The cutting blade of said inner diameter is used to cut said first bar to obtain an array of desired dimensions.
Obtaining a plurality of second bars by cutting the bar material deposit array of the second embodiment, wherein the second bars are separated by a second gap.
6. The method of claim 5, further comprising the steps of: disposing said bar on a fixture; and casting a reflector on the surface of said second bar and into said second gap. 7. A step of arranging a plurality of said first bar arrays to form a second deposit in order to cut said first bar into an array of a desired size; Cutting the second deposit using a blade to obtain a plurality of second bar deposits, separating the second bar deposit into a plurality of second rods, Disposing the second rod on the fixture while being separated by the gap, and casting a reflective material on the surface of the second rod and in the second gap. The method of claim 5, wherein 8. The method of claim 5, wherein X is about 1 mm, Y is about 3 mm, and Z is about 2 mm when the array of desired dimensions includes scintillator elements having dimensions of X × Y × Z. Method. 9. The method of claim 1, further comprising: disposing the first bar deposit on a fixture; separating the first bar deposit from each other to obtain an array; and depositing the first bar deposit. The method of claim 1 including the step of casting a reflector on the surface of the object. 10. The method of claim 9, wherein the step of separating the first bar deposits from each other to obtain an array creates a plurality of gaps. 11. The method of claim 10 wherein said gap has a width in the range of about 0.5 to 6 mils. 12. A method of manufacturing a scintillator for a computed tomography apparatus using an inner diameter saw having a saw blade having an inner peripheral cutting edge, wherein a plurality of scintillator wafers are combined to form a deposit. Using the cutting blade of the inner diameter to cut the deposit to obtain a plurality of first bar deposits; separating the first bar deposits from each other on a fixture; Casting a bar to form an array; cutting the first bar deposit using the cutting edge of the inner diameter to obtain a plurality of second bar deposits; Separating the second bar deposits from each other; casting a reflector to form an array; cutting the array to obtain a plurality of scintillators;
And casting a reflector around each of the scintillators. 13. The method according to claim 13, further comprising:
13. The method of claim 12, including the step of casting a reflector on the surface of the first bar deposit after separating the bar deposits from each other. 14. The method according to claim 14, further comprising:
13. The method of claim 12, including the step of casting a reflective material on the surface of said second bar deposit after separating said bar deposits from each other. 15. The method of claim 12, wherein the step of separating the first bar deposits on the fixture results in a plurality of gaps. 16. The method of claim 15, wherein said gap has a width in the range of about 0.5 to 6 mils. 17. The method of claim 15, wherein the thickness of the deposit is greater than ten times the width of the gap. 18. The method of claim 12, wherein the step of separating the second bar deposits on the fixture results in a plurality of second gaps. 19. The method of claim 18, wherein said second gap has a width in the range of about 0.5 to 6 mils.